Process for Preparing an Overbased Detergent

ABSTRACT

The invention relates to a process for preparing an overbased metal detergent in an oil medium comprising the steps of: (1) providing a metal salt selected from the group consisting of a hydrocarbyl-substituted organic acid; a hydrocarbyl-substituted phenol, a phenate, a hydrocarbyl-substituted carboxylate and mixtures thereof; (2) further providing methanol and a mixture of alcohols containing 2 to about 7 carbon atoms, wherein the mole ratio of methanol to the mixture of alcohols is about 2.2 or less, to form a mixture; (3) further providing a basic metal compound; (4) reacting the mixture of step (3) with carbon dioxide to form a carbonated overbased metal sulphonate; (5) performing steps (3) and (4) at least three additional times upon the product of step (4); (6) thereafter removing at least a portion of the water produced in steps (1)-(5) and of the alcohols introduced in step (2); (7) performing step (2) again, upon the product of step (6); (8) performing steps (3) and (4) at least two additional times upon the product of step (7); and (9) thereafter removing a substantial portion of the water and of the alcohols from the composition; wherein the oil medium is present in an amount such that the weight ratio of the acid corresponding to the metal salt of (1) to the oil medium is 0.3 to 1.4; and wherein step (6) is required when the hydrocarbyl-substituted organic acid is a hydrocarbyl-substituted sulphonic acid. The invention further relates to its use in internal combustion engines.

A sample of a salixarene substrate is prepared using a flange flaskapproximately 2 litres in volume, a flange and clip, overhead stirrerwith paddle and polytetrafluoroethylene (PTFE) stirrer gland, Dean Starktrap and double surface condenser, an electricmantle/thermocouple/Eurotherm™ temperature controller system, theglassware from just above the mantle to just below the condenser beingcovered with glass wool. The flask is filled with 475 g polyisobutenylphenol with a number average molecular weight of 550 (derived fromGLISSOPAL®550 commercially available from BASF) and 330 g of mineral oil(SN 150) and heated to 30° C. via a pressure equalizing dropping funnel3.4 g of 50% aqueous KOH is added. The contents of the flask heated to75° C. and the temperature is kept constant for 30 minutes while 81.6 gof 37% aqueous formaldehyde (formalin) is added. The reaction is chargedwith 51.6 g of salicylic acid and heated to 140° C. while controllingreflux. Water is removed using Dean Stark trap. The product is vacuumstripped at 140° C./13 kPa (equivalent to 100 mm Hg) for 30 minutes. Theproduct contains 2 methylene bridged polyisobutenyl phenol moleculesmethylene bridged to one salicylic acid. A more detailed description ofthe reaction process is given in Example 1 and 5 of InternationalPublication WO03/018728, pages 22 and 23.

FIELD OF INVENTION

The present invention relates to a process for preparing an overbasedmetal salt selected from the group consisting of ahydrocarbyl-substituted organic acid, a hydrocarbyl-substituted phenoland mixtures thereof. The overbased metal salt formed is suitable forapplication in an oil of lubricating viscosity.

BACKGROUND OF THE INVENTION

It is known to use overbased detergents in an oil of lubricatingviscosity to reduce engine wear and improve cleanliness. Overbaseddetergents include sulphonates, salixarates or salicylates, and theyprovide alkalinity to neutralize sulphur-containing acids produced fromthe combustion of carbonaceous fuels. These detergents are prepared by anumber of low and high temperature processes. However, the preparationof a highly overbased detergent is difficult because the in-processviscosity and final viscosity tend to be too viscous and the finalproduct is not soluble or lacks clarity or becomes too viscous to bereadily handle-able.

U.S. Pat. No. 6,444,625 (Muir et al.) discloses a method for preparing ahandle-able overbased metal sulphonate detergent having a TBN of 400 ormore, and having a viscosity of at least 180 mm²s⁻¹ (cSt) at 100° C. Theprocess for preparing the overbased sulphonate detergent requires asolvent system containing a hydrocarbon solvent and an alcohol with 1 to4 carbon atoms. However, the hydrocarbon solvent is known to beenvironmentally unfriendly requiring safe storage and disposal of waste.

It would be desirable to have a process for preparing an overbased metaldetergent that is handle-able, environmentally friendly, andsubstantially free of hydrocarbon solvent, in a cost effective manner.The present invention provides a process for preparing an overbasedmetal detergent that is handle-able, environmentally friendly, andsubstantially free of hydrocarbon solvent, in a cost effective manner.

SUMMARY OF THE INVENTION

The present invention provides a process for preparing an overbasedmetal detergent in an oil medium comprising the steps of:

-   -   (1) providing a metal salt selected from the group consisting of        a hydrocarbyl-substituted organic acid; a        hydrocarbyl-substituted phenol, a phenate, a        hydrocarbyl-substituted carboxylate and mixtures thereof;    -   (2) further providing methanol and a mixture of alcohols        containing 2 to about 7 carbon atoms, wherein the mole ratio of        methanol to the mixture of alcohols is about 2.2 or less, to        form a mixture;    -   (3) further providing a basic metal compound;    -   (4) reacting the mixture of step (3) with carbon dioxide to form        a carbonated overbased metal sulphonate;    -   (5) performing steps (3) and (4) at least three additional times        upon the product of step (4);    -   (6) thereafter removing at least a portion of the water produced        in steps (1)-(5) and of the alcohols introduced in step (2);    -   (7) performing step (2) again, upon the product of step (6);    -   (8) performing steps (3) and (4) at least two additional times        upon the product of step (7); and    -   (9) thereafter removing a substantial portion of the water and        of the alcohols from the composition;        wherein the oil medium is present in an amount such that the        weight ratio of the acid corresponding to the metal salt of (1)        to the oil medium is 0.3 to 1.4; and wherein step (6) is        required when the hydrocarbyl-substituted organic acid is a        hydrocarbyl-substituted sulphonic acid.

In one embodiment the invention provides a process for preparing anoverbased metal detergent in an oil medium comprising the steps of:

-   -   (1) providing a metal salt selected from the group consisting of        a hydrocarbyl-substituted organic acid; a        hydrocarbyl-substituted phenol, a phenate, a        hydrocarbyl-substituted carboxylate and mixture thereof;    -   (2) further providing methanol and a mixture of alcohols        containing 2 to about 7 carbon atoms, wherein the mole ratio of        methanol to the mixture of alcohols is about 2.2 or less, to        form a mixture;    -   (3) further providing a basic metal compound;    -   (4) reacting the mixture of step (3) with carbon dioxide to form        a carbonated overbased metal sulphonate;    -   (5) performing steps (3) and (4) at least three additional times        upon the product of step (4);    -   (6) thereafter removing at least a portion of the water produced        in steps (1)-(5) and of the alcohols introduced in step (2);    -   (7) performing step (2) again, upon the product of step (6);    -   (8) performing steps (3) and (4) at least two additional times        upon the product of step (7);    -   (9) thereafter removing a substantial portion of the water and        of the alcohols from the composition; and    -   (10) a processing step of filtering or stripping the product of        step (9) to form the overbased metal detergent,        wherein the process if free of co-surfactant or co-promoter        other than the mixture of alcohols; wherein the oil medium is        present in an amount such that the weight ratio of the acid        corresponding to the metal salt of (1) to the oil medium is 0.3        to 1.4; and wherein step (6) is required when the        hydrocarbyl-substituted organic acid is a        hydrocarbyl-substituted sulphonic acid.

The invention further provides the overbased metal detergent that ishandle-able and environmentally friendly.

The invention further provides a method for lubricating an internalcombustion engine, comprising supplying thereto a lubricant comprisingthe overbased metal detergent as described herein.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process for preparing an overbasedmetal detergent in an oil medium as described above.

As used herein the Total Base Number is a measure of the final overbaseddetergent containing the oil used in processing i.e. the final producthas not been diluted in additional oil nor has oil been removed afterprocessing.

The metal salt of step (1) is prepared by techniques known to thoseskilled in the art. Steps (1) to (3) are preferably carried out in thisorder. However, variations of the preferred order are also encompassedby this invention.

As used herein the term “free of”, as used in the specification andclaims, defines the absence of a material except for the amount which ispresent as impurities, e.g., a trace amount. Typically in thisembodiment, the amount present will be less than about 0.05% or lessthan about 0.005 wt % by weight of the lubricating composition.

In one embodiment the process is carried out free of co-surfactant orco-promoter other than the mixture of alcohols. Known co-surfactant orco-promoter chemistry includes a calcium salt of a formaldehyde coupledaliphatic phenol, hydroxy-sulphonic acids, inorganic halides (such asammonium halides, alkaline earth metal halides especially calciumchloride or alkali metal halides) or an inorganic calcium salt, such as,calcium nitrate. In one embodiment the co-surfactant or co-promoter areselected from the group consisting of a calcium salt of formaldehydecoupled aliphatic phenols, a hydroxy-sulphonic acids, inorganic halidesor inorganic calcium salts.

The processing step of filtering or stripping the product of step (9) toform the overbased metal detergent may be carried out by known processto a person skilled in the art. Typically, the processing step mayemploy stripping carried out by nitrogen blowing or an elevated flashstripping process. Filtering or clarification may be carried out using afilter aid and support. A common filter aid is a diatomaccous earthfilter in a suitable filtration system.

The process preferably results in any residual solids and residual waterand alcohols being substantially completely removed from the product. Asused herein the term “substantially completely” results in any residualsolids and residual water and alcohols each being present at less thanor equal to 2 wt %, preferably less than less than or equal to 1.8 wt %,more preferably less than or equal to 1.5 wt % and most preferably lessthan or equal to 1.2 wt % of the final product.

The process of step (3) often adds 5 to 40, preferably 7 to 30 and mostpreferably 10 to 20 percent by weight of the total amount of the basicmetal compound is added at each occurrence of addition step (3). Theamount of metal compound added at each addition can be the same ordifferent.

The process of step (9) requires the removal of at least a portion ofthe water, often carried out by flash stripping. Often the flashstripping is carried out at a temperature of at least 115° C.,preferably at least 125° C., more preferably at least 135° C. and mostpreferably at least 140° C.

Hydrocarbon Solvent

The process of the present invention is preferably substantially free ofhydrocarbon solvent. As used herein, the term “substantially free ofhydrocarbon solvent other than the oil of lubricating viscosity” is usedto describe the presence of a solvent system containing the mixture ofalcohols described below with less than 10 wt %, preferably less than 5wt %, more preferably less than 2 wt % and most preferably less than 0.5wt % hydrocarbon solvent present in the process. In one embodiment, theprocess is free of hydrocarbon solvent other than the oil of lubricatingviscosity.

If present, hydrocarbon solvents can include aliphatic hydrocarbons oraromatic hydrocarbons. Examples of suitable aliphatic hydrocarbonsinclude hexane, heptane, octane, nonane, decane, undecane, dodecane,tridecane and mixtures thereof. Examples of suitable aromatichydrocarbons include benzene, xylene, toluene and mixtures thereof.

The Metal Basic Compound

The metal basic compound is used to supply excess basicity to theoverbased material. The metal basic compound can be a hydroxide or oxideof the metal. The metal can be monovalent, divalent, or trivalent. Whenmonovalent, the metal ion M can be an alkali metal, preferably lithium,sodium, or potassium; and more preferably potassium, which can be usedalone or in combination with other metals. When divalent, the metal ionM can be an alkaline earth metal, preferably magnesium, calcium, bariumor mixtures thereof, more preferably calcium, which can be used alone orin combination with other metals. When trivalent, the metal ion M can bealuminium, which can be used alone or in combination with other metals.

Suitable examples of metal basic compounds with hydroxide functionalityinclude lithium hydroxide, potassium hydroxide, sodium hydroxide,magnesium hydroxide, calcium hydroxide, barium hydroxide and aluminiumhydroxide. Suitable examples of metal basic compounds with oxidefunctionality include lithium oxide, magnesium oxide, calcium oxide andbarium oxide. The oxides and/or hydroxides can be used alone or incombination. The oxides or hydroxides can be hydrated or dehydrated,although hydrated is preferred. In one embodiment the metal basiccompound is calcium hydroxide, which can be used alone or mixturesthereof with other metal basic compounds. Calcium hydroxide is oftenreferred to as lime. In one embodiment the metal basic compound iscalcium oxide which can be used alone or mixtures thereof with othermetal basic compounds.

The Overbased Material

Overbased materials, otherwise referred to as overbased or superbasedsalts, are generally single phase, homogeneous Newtonian systemscharacterised by a metal content in excess of that which would bepresent for neutralisation according to the stoichiometry of the metaland the particular acidic organic compound reacted with the metal.

The amount of excess metal is commonly expressed in terms of substrateto metal ratio. The terminology “metal ratio” is used in the prior artand herein to designate the ratio of the total chemical equivalents ofthe metal in the overbased salt to the chemical equivalents of the metalin the salt which would be expected to result in the reaction betweenthe hydrocarbyl-substituted organic acid; the hydrocarbyl-substitutedphenol or mixtures thereof to be overbased and the basically reactingmetal compound according to the known chemical reactivity andstoichiometry of the two reactants. Thus, in a normal or neutral saltthe metal ratio is one and, in an overbased salt, the metal ratio isgreater than one. The overbased metal salt of thehydrocarbyl-substituted organic acid; the hydrocarbyl-substituted phenolor mixtures thereof used in this invention usually have metal ratios notexceeding 40:1 (or 40). Often, salts having ratios of 2:1 to 35:1 areused.

Metal Salt of a Hydrocarbyl-Substituted Organic Acid or aHydrocarbyl-Substituted Phenol

In one embodiment of the invention the metal salt selected from thegroup consisting of a hydrocarbyl-substituted organic acid, ahydrocarbyl-substituted phenol and mixtures thereof, includes a metalsalt derived from a hydrocarbyl-substituted sulphonic acid, ahydrocarbyl-substituted hydroxy-aromatic acid (preferablyhydroxy-benzoic acid) such as a metal salixarate or a metal salt ofhydrocarbyl-salicylate.

Metal Salixarate

In one embodiment of the invention a substrate of the metal salixarateof the invention includes those represented by a substantially linearcompound comprising at least one unit of the formulae (I) or (II):

each end of the compound having a terminal group of formulae (III) or(IV):

such groups being linked by divalent bridging groups B, which may be thesame or different for each linkage; wherein in formulas (I)-(IV) R³ ishydrogen or a hydrocarbyl group; R² is hydroxyl or a hydrocarbyl groupand j is 0, 1, or 2; R⁶ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; either R⁴ is hydroxyl and R⁵ andR⁷ are independently either hydrogen, a hydrocarbyl group, orhetero-substituted hydrocarbyl group, or else R⁵ and R⁷ are bothhydroxyl and R⁴ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; provided that at least one of R⁴,R⁵, R⁶ and R⁷ is hydrocarbyl containing at least 8 carbon atoms; andwherein the molecules on average contain at least one of unit (I) or(III) and at least one of unit (II) or (IV) and the ratio of the totalnumber of units (I) and (III) to the total number of units of (II) and(IV) in the composition is about 0.1:1 to about 2:1.

The hydroxyl group in formulae (i) and (iii) may be located in aposition ortho, meta, para or mixtures thereof to the —COOR³ group.Preferably the hydroxyl group is located in an ortho to the —COOR³group.

The divalent bridging group “A,” which may be the same or different ineach occurrence, includes —CH₂— (methylene bridge) and —CH₂OCH₂— (etherbridge), either of which may be derived from formaldehyde or aformaldehyde equivalent (e.g., paraform, formalin).

It is believed that the salixarate derivatives have a predominantlylinear, rather than macrocyclic, structure, although both structures areintended to be encompassed by the term “salixarate.”

It is believed that a significant fraction of salixarate molecules(prior to neutralisation) may be represented on average by the followingformula:

wherein each R⁸ can be the same or different, and are hydrogen, an alkylgroup or mixtures thereof provided at least one R⁸ is alkyl. In apreferred embodiment, is a polyisobutene group (especially of molecularweight 200 to 1,000, or about 550). Significant amounts of di-ortrinuclear species may also be present containing one salicylic endgroup of formula (III). The salixarate detergent may be used alone orwith other detergents.

In one embodiment the overbased metal salt of hydrocarbyl-substitutedorganic acid is the metal salt of the hydrocarbyl-substitutedhydroxy-aromatic acid (preferably hydroxy-benzoic acid) such as a metalsalixarate, and the metal ratios are often 5:1 to 35:1. Often the metalratio is at least 8, preferably at least 12, more preferably at least 15and most preferably at least 17.

Often the overbased metal salt of hydrocarbyl-substitutedhydroxy-aromatic acid (preferably hydroxy-benzoic acid) is a detergentespecially a metal salixarate with a TBN (Total Base Number) of at least80, more preferably at least 90, and more preferably at least 110, evenmore preferably at least 120. In one embodiment the overbased salixaratedetergent has a TBN of about 124. In one embodiment the overbasedsalixarate detergent has a TBN of about 280.

In one embodiment of the invention the metal salt selected from thegroup consisting of a hydrocarbyl-substituted organic acid, ahydrocarbyl-substituted phenol and mixtures thereof, includes a metalsalt of a hydrocarbyl-salicylate including those represented by theformula:

wherein M is a valence of a metal ion, n is an integer equal to or lessthan the available valence of M. R⁹ is a hydrocarbyl group. Preferablythe hydrocarbyl group has 6 to 50, preferably 8 to 30 and mostpreferably 8 to 25 carbon atoms; and the hydrocarbyl group includescyclic acyclic moieties or mixtures thereof. The hydrocarbyl group ispreferably selected from the group consisting of an alkyl, cycloalkyl,aryl, acyl and mixtures thereof. Most preferably the hydrocarbyl groupis an alkyl group.

The COO group is positioned at an ortho, meta or para position relativeto the hydroxyl group; preferably the ortho, para position or mixturesthereof; and most preferably at the otho position. When the COO group isortho to the hydroxyl group the hydrocarbyl-substituted salicylic acidis a hydrocarbyl-substituted 1,2-salicylic acid. When the COO group ismeta to the hydroxyl group the hydrocarbyl-substituted salicylic acid isa hydrocarbyl-substituted 3-hydroxyaromatic acid. When the COO group ispara to the hydroxyl group the hydrocarbyl-substituted salicylic acid isa hydrocarbyl-substituted 3-hydroxyaromatic acid.

Examples of a hydrocarbyl group independently suitable for R⁹ includeoctyl, n-octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl,nonodecyl, eicosyl, iso-nonyl, iso-decyl, iso-undecyl, iso-dodecyl,iso-tridecyl, iso-tetradecyl, iso-pentadecyl, iso-hexadecyl,iso-heptadecyl, iso-octadecyl, iso-octadecenyl, iso-nonodecyl,iso-eicosyl or mixtures thereof.

M is a valence the metal ion and may be monovalent, divalent, trivalentor mixtures of such metals. When monovalent, the metal M can be analkali metal, preferably lithium, sodium, or potassium; and morepreferably potassium, which can be used alone or in combination withother metals. When divalent, the metal M can be an alkaline earth metal,preferably magnesium, calcium, barium or mixtures of such metals, morepreferably calcium, which can be used alone or in combination with othermetals. When trivalent, the metal M may be aluminium, which can be usedalone or in combination with other metals. In one embodiment the metalis an alkaline earth metal. In one embodiment the metal is calcium,which can be used alone or in combination with other metals.

In one embodiment the overbased metal salt of hydrocarbyl-substitutedorganic acid is the metal salt of hydrocarbyl-salicylate and the metalratios are often 5:1 to 35:1. Often the metal ratio is at least 8,preferably at least about 12, more preferably at least about 15 and mostpreferably at least about 17. Often the overbased metal salt of metalsalt of hydrocarbyl-salicylate is a detergent especially with a TBN ofat least 80, more preferably at least 90, and more preferably at least110, even more preferably at least 120.

Metal Salt of a Hydrocarbyl-Substituted Sulphonic Acid

In one embodiment of the invention the metal salt selected from thegroup consisting of a hydrocarbyl-substituted organic acid, ahydrocarbyl-substituted phenol and mixtures thereof, includes a metalsalt of the hydrocarbyl-substituted sulphonic acid including thoserepresented by the formula:(R¹⁰)_(k)—A—SO₃M   (VII)wherein, each R¹⁰ is independently a hydrocarbyl group. Preferably thehydrocarbyl group has 6 to 40, preferably 8 to 35 and most preferably 9to 30 carbon atoms; A can be cyclic or acyclic moieties or mixturesthereof. The hydrocarbyl group is preferably selected from the groupconsisting of an alkyl, cycloalkyl, aryl, acyl and mixtures thereof.Most preferably the hydrocarbyl group is an alkyl group.

In one embodiment k is 1 and R¹⁰ is a branched alkyl group with 6 to 40carbon atoms. In one embodiment k is 1 and R¹⁰ is a linear or branchedalkyl group with 6 to 40 carbon atoms. M is a valence of a metal ion, asdefined above.

The metal salt of the hydrocarbyl-substituted sulphonic acid has ahydrocarbyl-substituted sulphonic group that includes natural, syntheticor mixtures thereof. Suitable examples of the hydrocarbyl-substitutedsulphonic acid include polypropene benzenesulphonic acid; and monoalkyland dialkyl benzenesulphonic acids wherein the alkyl groups contain atleast 10 carbons for example, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30 and mixtures thereof.

Examples of a suitable alkyl group include branched and/or linear decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, octadecenyl, nonodecyl, eicosyl, un-eicosyl,do-eicosyl, tri-eicosyl, tetra-eicosyl, penta-eicosyl, hexa-eicosyl ormixtures thereof

Preferred examples of hydrocarbyl-substituted sulphonic acid includepolypropene benzenesulphonic acid and C₁₆-C₂₄ alkyl benzenesulphonicacid or mixtures thereof.

When A is cyclic suitable groups include phenyl or fused bicyclic suchas naphthalene, indenyl, indanyl, bicyclopentadienyl and mixturesthereof. Although A includes a fused bicyclic ring, phenyl rings arepreferred.

When A is a chain, the chain can be linear, branched and mixturesthereof, although linear is preferred. Suitable groups includederivatives of carboxylic acids containing 7 to 30, preferably 7 to 20,more preferably 8 to 20 and most preferably 8 to 15 carbon atoms.Further the chain can be saturated or unsaturated, although saturated ispreferred.

In one embodiment the overbased metal salt of hydrocarbyl-substitutedorganic acid is the metal salt of the hydrocarbyl-substituted sulphonicacid and the metal ratios are often 10:1 to 35:1. Often the metal ratiois at least 20, preferably at least about 22, more preferably at leastabout 25 and most preferably at least about 27.

The overbased detergent often has a low in-process viscosity and a lowfinal viscosity. As used herein the term “low” used in “low in-processviscosity” and a “low final viscosity” defines a viscosity that is lowerthan would be expected from a conventional overbased metal detergent.

The final product often has a handle-able final viscosity of less than300 mm²s⁻¹, preferably less than 200 mm²s⁻¹, more preferably less than190 mm²s⁻¹ and most preferably less than 180 mm²s⁻¹ at 100° C.

Often the overbased metal salt of hydrocarbyl-substituted sulphonic acidis a detergent especially an overbased metal sulphonate with a TBN(Total Base Number) of at least 400, more preferably at least 425, andmore preferably at least 450, even more preferably at least 490. In oneembodiment the overbased sulphonate detergent has a TBN of about 500.

In one embodiment of the invention provides in step (1) a metal salt ofa phenate such as a sulphur containing phenate, a alkylene (preferablymethylene) coupled phenate or mixtures thereof. The preparation of thephenate materials listed above are known in the art.

In one embodiment of the invention provides in step (1) a metal salt ofa hydrocarbyl-substituted carboxylate or mixtures thereof. Examples of asuitable carboxylic acid used to prepare the hydrocarbyl-substitutedcarboxylate include 2-methyl-2-heptenoic acid, 5-methyl-2-hexenoic acid,3-methyl-2-heptenoic acid, 2,4,4-trimethyl-2-pentenoic acid,4,4-dimethyl-2-pentenoic acid, 3-ethyl-2-hexenoic acid, 2-heptenoicacid, 2,3-dimethyl-2-pentenoic acid, 3,5-dimethyl-2-hexenoic acid,2-methyl-2-pentenoic acid, 3,4,4-trimethyl-2-pentenoic acid,3-propyl-2-hexenoic acid, 4-methyl-2-pentenoic acid,2,4-dimethyl-2-pentenoic acid, 3-ethyl-2-pentenoic acid,3,4-dimethyl-2-pentenoic acid, 4-methyl-2-hexenoic acid,2,4-dimethyl-2-hexenoic acid, 3-butyl-2-heptenoic acid,2,5-dimethyl-2-hexenoic acid, 2-methyl-2-hexenoic acid,3-ethyl-2-methyl-2-pentenoic acid, decanoic acid, isodecanoic acid,dodecanoic acid, tridecanoic acid, butadecanoic acid, myristic acid,pentadecanoic acid, palmitic acid, hexadecanoic acid, heptadecanoicacid, stearic acid, octacdecanoic acid, icosyldecanoic acid, icosanoicacid or mixtures thereof.

Mixture of Alcohols

The alcohols include methanol and a mixture of alcohols containing 2 to7, preferably 2 to 6, more preferably 2 to 5 and most preferably 3 to 5carbon atoms. The mixture of alcohols containing 2 to 7 carbon atoms caninclude branched or linear alkyl chains or mixtures thereof, althoughbranched is preferred.

The mixture of alcohols can contain ethanol, propan-1-ol, propan-2-ol,isopropanol, butan-1-ol, butan-2-ol, isobutanol, pentan-1-ol,pentan-2-ol, pentan-3-ol, isopentanol, hexan-1-ol, hexan-2-ol,hexan-3-ol, heptan-1-ol, heptan-2-ol, heptan-3-ol, heptan-4-ol ormixtures thereof. Preferably the mixture of alcohols contains at leastone butanol and at least one amyl alcohol. The mixture of alcohols iscommercially available as isoamyl alcohol from Union Carbide or othersuppliers.

The mole ratio of methanol to the mixture of alcohols is often below2.2, preferably 1.70, more preferably 0.9 to 1.60, even more preferably1 to 1.50, even more preferably 1 to 1.45 and most preferably 1.1 to1.40.

In one embodiment the hydrocarbyl-substituted organic acid is the metalsalt of the hydrocarbyl-substituted sulphonic acid and the mole ratio ofmethanol to the mixture of alcohols is often below 1.7, preferably 0.9to 1.60, more preferably 1 to 1.50, even more preferably 1 to 1.45 andmost preferably 1.1 to 1.40.

In one embodiment the hydrocarbyl-substituted organic acid is the metalsalt of hydrocarbyl-substituted hydroxy-aromatic acid such as a metalsalixarate and the mole ratio of methanol to the mixture of alcohols isoften less than 2.2, preferably less than 2.1, more preferably 0.9 to2.05, more preferably 1 to 2, even more preferably 1.2 to 2 and mostpreferably 1.2 to 1.95.

The amount of methanol and a mixture of alcohols containing 2 to 7carbon atoms present in the solvent system is more than 90 wt %,preferably more than 95 wt %, more preferably more than 98 wt % and mostpreferably more than 99.5 wt %. In one embodiment the solvent systemcontains only methanol and a mixture of alcohols containing 2 to 7carbon atoms.

Oil Medium

The invention further includes an oil medium (considered to be distinctand not part of the hydrocarbon solvent described above), especially anoil of lubricating viscosity. The oil includes natural and syntheticoils, oil derived from hydrocracking, hydrogenation, hydrofinishing,unrefined, refined and re-refined oils, or mixtures thereof.

Unrefined oils are those obtained directly from a natural or syntheticsource generally without (or with little) further purificationtreatment.

Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Purification techniques are known in the art and includesolvent extraction, secondary distillation, acid or base extraction,filtration, percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and areobtained by processes similar to those used to obtain refined oils andoften are additionally processed by techniques directed to removal ofspent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animaloils, vegetable oils (e.g., castor oil, lard oil), mineral lubricatingoils such as liquid petroleum oils and solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types and oils derived from coal or shale ormixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils suchas polymerised and interpolymerised olefins (e.g., polybutylenes,polypropylenes, propyleneisobutylene copolymers); poly(1-hexenes),poly(1-octenes), poly(1-decenes), and mixtures thereof; alkyl-benzenes(e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di-(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls,alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenylsulphides and the derivatives, analogs and homologs thereof or mixturesthereof.

Other synthetic lubricating oils include liquid esters ofphosphorus-containing acids (e.g., tricresyl phosphate, trioctylphosphate, and the diethyl ester of decane phosphonic acid), andpolymeric tetrahydrofurans. Synthetic oils may be produced byFischer-Tropsch reactions and often may be hydroisomerisedFischer-Tropsch hydrocarbons or waxes.

Oils of lubricating viscosity can also be defined as specified in theAmerican Petroleum Institute (API) Base Oil InterchangeabilityGuidelines. The five base oil groups are as follows: Group I (sulphurcontent >0.03 wt %, and/or <90 wt % saturates, viscosity index 80-120);Group II (sulphur content ≦0.03 wt %, and ≧90 wt % saturates, viscosityindex 80-120); Group III (sulphur content ≦0.03 wt %, and ≧90 wt %saturates, viscosity index ≧120); Group IV (all polyalphaolefins(PAOs)); and Group V (all others not included in Groups I, II, III, orIV). The oil of lubricating viscosity comprises an API Group I, II, III,IV, V oil and mixtures thereof. Preferably the oil of lubricatingviscosity is an API Group I, II, III oil or mixtures thereof.

Optional Performance Additives

The detergent can be incorporated into a lubricating oil compositionthat optionally includes at least one other performance additiveselected from the group consisting of metal deactivators, detergentsother than those prepared by the process of the invention, dispersants,antioxidants, antiwear agents, corrosion inhibitors, antiscuffingagents, extreme pressure agents, foam inhibitors, demulsifiers, frictionmodifiers, viscosity modifiers, pour point depressants and mixturesthereof. Often fully-formulated lubricating oil will contain one or moreof these additives.

Industrial Application

The metal salt selected from the group consisting of ahydrocarbyl-substituted organic acid; a hydrocarbyl-substituted phenoland mixtures thereof of the present invention are useful as detergentsin lubricants for internal combustion engines, for example dieselfuelled engines, gasoline fuelled engines, natural gas fuelled enginesor mixed gasoline/alcohol fuelled engines.

In one embodiment of the invention provides a method for lubricating aninternal combustion engine, comprising supplying thereto a lubricantcomprising the composition as described herein. The invention issuitable for 2-stroke or 4-stroke engines, in particular marine dieselengines, especially 2-stroke marine diesel engines.

The following examples provide an illustration of the invention. Theseexamples are non exhaustive and are not intended to limit the scope ofthe invention.

EXAMPLES Preparative Example 1

Preparation of Salixarate Substrate—Salixarene

A sample of a salixarene substrate is prepared using a flange flaskapproximately 2 litres in volume, a flange and clip, overhead stirrerwith paddle and polytetrafluoroethylene (PTFE) stirrer gland, Dean Starktrap and double surface condenser, an electricmantle/thermocouple/Eurotherm™ temperature controller system, theglassware from just above the mantle to just below the condenser beingcovered with glass wool. The flask is filled with 475 g polyisobutenylwith a number average molecular weight of 550 (derived fromGLISSOPAL®550 commercially available from BASF) and 330 g of mineral oil(SN 150) and heated to 30° C. via a pressure equalizing dropping funnel3.4 g of 50% aqueous KOH is added. The contents of the flask heated to75° C. and the temperature is kept constant for 30 minutes while 81.6 gof 37% aqueous formaldehyde (formalin) is added. The reaction is chargedwith 51.6 g of salicylic acid and heated to 140° C. while controllingreflux. Water is removed using Dean Stark trap. The product is vacuumstripped at 140° C./13 kPa (equivalent to 100 mm Hg) for 30 minutes. Theproduct contains 2 methylene bridged polyisobutenyl phenol moleculesmethylene bridged to one salicylic acid. A more detailed description ofthe reaction process is given in Example 1 and 5 of InternationalPublication WO03/018728, pages 22 and 23.

Example 1

Preparation of 124 TBN Calcium Salixarate

A vessel equipped with a stirrer, sparging tube, thermowell andcondenser is charged with 63.4 parts by weight of the product ofPreparative Example 1 and 14.7 parts by weight of oil. The reactor ischarged with 12.1 parts by weight of a methanol and a mixture ofiso-butanol/amyl alcohol. The ratio of methanol to the mixture ofiso-butanol/amyl alcohol is 1.88. The reactor is charged with 9.7 partsby weight of calcium hydroxide, 1.2 parts by weight water and 0.05 partsby weight acetic acid and the mixture is heated to 54° C. at which pointcarbon dioxide is added to form a carbonated product. The carbonatedproduct is further treated three more times with similar (or equal)portions of calcium hydroxide and carbon dioxide. Water is removed bystripping before repeating the addition of alcohol, calcium hydroxideand carbon dioxide 2 times. The product is stripped and filtered.

Example 2 is the same as example 1 except it is carried out on a largerscale.

Example 3

Preparation of 280 TBN Calcium Salixarate

Example 3 is prepared in the same process as Example 1, except thereactor is charged with 47.7 parts by weight of the product ofPreparative Example 1 and 26.5 parts by weight of oil 21.8 parts byweight of a methanol and a mixture of iso-butanol/amyl alcohol. Theratio of methanol to the mixture of iso-butanol/amyl alcohol is 1.63.The reactor is charged with 4 parts by weight of calcium hydroxide, 0.1parts by weight water and 0.03 parts by weight acetic acid and themixture is heated to 54° C. where carbon dioxide is added to form acarbonated product. The carbonated product is further treated three moretimes with similar (or equal) portions of calcium hydroxide and carbondioxide. Water is removed by stripping before repeating the addition ofalcohol, calcium hydroxide and carbon dioxide 2 times. The product isstripped and filtered.

Example 4

Preparation of Calcium Salixarate

Example 4 is prepared in a similar manner to Example 1 except themethanol to the mixture of iso-butanol/amyl alcohol is 1.91.

Example 5

Preparation of Calcium Salixarate

Example 5 is prepared in a similar manner to Example 3 except 6.8 partsby weight of calcium hydroxide is used.

Example 6

Preparation of Calcium Salixarate

The process is the same as Example 1 except the number of times thesteps repeating the addition of alcohol, calcium hydroxide and carbondioxide after the stripping of water is 3 instead 2.

Example 7

Preparation of Calcium Hexadecyl Salicylate

The process is the same as Example 1 except hexadecyl salicylic acid isused instead of the product from Preparative Example 1.

Example 8

Preparation of Calcium Hexadecyl Salicylate

The process is the same as Example 7 except the ratio of methanol to themixture of iso-butanol/amyl alcohol is 1.73.

Example 9

Preparation of Calcium Hexadecyl Salicylate

The process is the same as Example 7 except the number of times thesteps repeating the addition of alcohol, calcium hydroxide and carbondioxide after the stripping of water is 3 instead 2.

Example 10

Preparation of 500 TBN Calcium Sulphonate

A sample of a 500 TBN sulphonate detergent is prepared using a flangevessel, a flange and clip, overhead stirrer with paddle andpolytetrafluoroethylene (PTFE) stirrer gland, Dean Stark trap and doublesurface condenser, a mantle/thermocouple temperature controller system,the equipment from just above the mantle to just below the condenserbeing covered with glass wool. The vessel is charged with 35.1 parts byweight of C₁₆-C₂₄ alkylbenzene sulphonic acid and 31.8 parts by weightof mineral oil (SN 150) and heated to 30° C. The reactor is chargedthrough a port with alcohols containing methanol and a mixture ofiso-butanol/amyl alcohol present at 11.6 parts by weight. The weightratio of methanol to the mixture of iso-butanol/amyl alcohol is 1.31.The reactor is charged with 14.9 parts by weight of calcium hydroxideand the mixture is heated to 54° C. at which point carbon dioxide isadded to form a carbonated product. The carbonated product is furthertreated three more times with similar (or equal) portions of calciumhydroxide and carbon dioxide. Water is removed by stripping beforerepeating the addition of alcohol, calcium hydroxide and carbon dioxide2 times. The product is stripped and filtered.

Example 11

Preparation of Calcium Sulphonate

The process is the same as Example 10 except the number of times thesteps repeating the addition of alcohol, calcium hydroxide and carbondioxide after the stripping of water is 3 instead 2.

Example 12

Preparation of Calcium Sulphonate

The process is the same as Example 10 except a mixture of polypropylenealkylbenzene sulphonic acid is used instead of the mixture of C₁₆-C₂₄alkylbenzene sulphonic acid.

Example 13

Preparation of Calcium Sulphonate

The process is the same as Example 10 except the methanol to mixture ofiso-butanol/amyl alcohol ratio is 1.19.

In this specification the terms “hydrocarbyl substituent” or“hydrocarbyl group,” as used herein are used in its ordinary sense,which is well-known to those skilled in the art. Specifically, it refersto a group having a carbon atom directly attached to the remainder ofthe molecule and having predominantly hydrocarbon character. Examples ofhydrocarbyl groups include:

hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-,aliphatic-, and alicyclic-substituted aromatic substituents, as well ascyclic substituents wherein the ring is completed through anotherportion of the molecule (e.g., two substituents together form a ring);

substituted hydrocarbon substituents, that is, substituents containingnon-hydrocarbon groups which, in the context of this invention, do notalter the predominantly hydrocarbon nature of the substituent (e.g.,halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto,alkylmercapto, nitro, nitroso, and sulfoxy);

hetero substituents, that is, substituents which, while having apredominantly hydrocarbon character, in the context of this invention,contain other than carbon in a ring or chain otherwise composed ofcarbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, andencompass substituents as pyridyl, furyl, thienyl and imidazolyl. Ingeneral, no more than two, preferably no more than one, non-hydrocarbonsubstituent will be present for every ten carbon atoms in thehydrocarbyl group; typically, there will be no non-hydrocarbonsubstituents in the hydrocarbyl group.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about.” Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil, which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.Similarly, the ranges and amounts for each element of the invention canbe used together with ranges or amounts for any of the other elements.As used herein, the expression “consisting essentially of” permits theinclusion of substances that do not materially affect the basic andnovel characteristics of the composition under consideration

While the invention has been explained, it is to be understood thatvarious modifications thereof will become apparent to those skilled inthe art upon reading the specification. Therefore, it is to beunderstood that the invention disclosed herein is intended to cover suchmodifications as fall within the scope of the appended claims.

1. A process for preparing an overbased metal detergent in an oil mediumcomprising the steps of: (1) providing a metal salt selected from thegroup consisting of a hydrocarbyl-substituted organic acid; ahydrocarbyl-substituted phenol, a phenate, a hydrocarbyl-substitutedcarboxylate and mixtures thereof; (2) further providing methanol and amixture of alcohols containing 2 to about 7 carbon atoms, wherein themole ratio of methanol to the mixture of alcohols is about 2.2 or less,to form a mixture; (3) further providing a basic metal compound; (4)reacting the mixture of step (3) with carbon dioxide to form acarbonated overbased metal sulphonate; (5) performing steps (3) and (4)at least three additional times upon the product of step (4); (6)thereafter removing at least a portion of the water produced in steps(1)-(5) and of the alcohols introduced in step (2); (7) performing step(2) again, upon the product of step (6); (8) performing steps (3) and(4) at least two additional times upon the product of step (7); and (9)thereafter removing a substantial portion of the water and of thealcohols from the composition; wherein the oil medium is present in anamount such that the weight ratio of the acid corresponding to the metalsalt of (1) to the oil medium is 0.3 to 1.4; and wherein step (6) isrequired when the hydrocarbyl-substituted organic acid is ahydrocarbyl-substituted sulphonic acid.
 2. The process of claim 1,wherein the process further comprises a processing step of filtering orstripping the product of step (9) to form the overbased metal detergent.3. The process of claim 1, wherein the process is free of co-surfactantor co-promoter other than the mixture of alcohols.
 4. The process ofclaim 1, wherein any residual solids and any residual water and alcoholsare substantially completely removed from the product.
 5. The process ofclaim 1 wherein about 10 to about 20 percent by weight of the totalamount of the basic metal compound is added at each occurrence of step(3).
 6. The process of claim 1 wherein the basic metal compound iscalcium oxide or calcium hydroxide or mixtures thereof.
 7. The processof claim 1, wherein the mixture of alcohols contains at least onebutanol and at least one amyl alcohol.
 8. The process of claim 1,wherein the removal of at least a portion of the water in step (9) iscarried out by flash stripping.
 9. The process of claim 8, wherein theflash stripping is carried out at a temperature of at least about 125°C.
 10. The process of claim 1, wherein the oil medium is substantiallyfree of hydrocarbon solvent other than oil of lubricating viscosity. 11.The process of claim 1, wherein the metal salt of step (1) is a metalsalt of a hydrocarbyl-substituted sulphonic acid is represented by theformula:(R¹)_(k)—A—SO₃M wherein each R¹ is independently a hydrocarbyl grouphaving about 6 to about 40 carbon atoms; A is a cyclic or acyclichydrocarbon group; M is a valence of at least one metal ion; and k is 1to about
 5. 12. The process of claim 11 wherein M is a valence ofcalcium.
 13. The process of claim 11, wherein the total base number ofthe metal salt of the hydrocarbyl-substituted sulphonic acid is at leastabout
 400. 14. The process of claim 11, wherein the metal ratio of themetal salt of the hydrocarbyl-substituted sulphonic acid is at leastabout
 20. 15. The process of claim 11, wherein the metal salt of thehydrocarbyl-substituted sulphonic acid is prepared using a mole ratio ofmethanol to the mixture of alcohols of about 1 to about 1.45.
 16. Theprocess of claim 1, wherein the metal salt of step (1) is a metalsalixarate.
 17. The process of claim 16, wherein M is a valence ofcalcium.
 18. The process of claim 16, wherein the total base number ofthe metal salt of the salixarate is at least about
 90. 19. The processof claim 16, wherein the metal salt of the salixarate is prepared usinga mole ratio of methanol to the mixture of alcohols of less than about2.2.
 20. The detergent prepared by the process of claim
 1. 21. A processfor lubricating an internal combustion engine, comprising supplyingthereto a lubricant composition comprising the detergent of claim 20.22. The process of claim 1, wherein the co-surfactant or co-promoter areselected from the group consisting of a calcium salt of formaldehydecoupled aliphatic phenols, a hydroxy-sulphonic acids, inorganic halidesor inorganic calcium salts.
 23. A process for preparing an overbasedmetal detergent in an oil medium comprising the steps of: (1) providinga metal salt selected from the group consisting of ahydrocarbyl-substituted organic acid; a hydrocarbyl-substituted phenol,a phenate, a hydrocarbyl-substituted carboxylate and mixtures thereof;(2) further providing methanol and a mixture of alcohols containing 2 toabout 7 carbon atoms, wherein the mole ratio of methanol to the mixtureof alcohols is about 2.2 or less, to form a mixture; (3) furtherproviding a basic metal compound; (4) reacting the mixture of step (3)with carbon dioxide to form a carbonated overbased metal sulphonate; (5)performing steps (3) and (4) at least three additional times upon theproduct of step (4); (6) thereafter removing at least a portion of thewater produced in steps (1)-(5) and of the alcohols introduced in step(2); (7) performing step (2) again, upon the product of step (6); (8)performing steps (3) and (4) at least two additional times upon theproduct of step (7); (9) thereafter removing a substantial portion ofthe water and of the alcohols from the composition; and (10) aprocessing step of filtering or stripping the product of step (9) toform the overbased metal detergent, wherein the process is free ofco-surfactant or co-promoter other than the mixture of alcohols; whereinthe oil medium is present in an amount such that the weight ratio of theacid corresponding to the metal salt of (1) to the oil medium is 0.3 to1.4; and wherein step (6) is required when the hydrocarbyl-substitutedorganic acid is a hydrocarbyl-substituted sulphonic acid.